Radar receive-antenna arrays with two closely spaced elements (e.g. spaced apart one half-wavelength) and one widely spaced element (e.g. spaced apart multiple wavelengths) have been proposed. The reflected signals detected by each antenna element may be used to synthesize or determine a virtual phase difference that corresponds to the reflected signal expected to be detected by a virtual element located between the two closely spaced antenna elements and the widely spaced antenna element. Phase comparison mono-pulse (PCMP) uses a phase difference of detected signals from the narrow spaced antenna elements to estimate a virtual phase difference for a virtual element based on the separation or spacing of the virtual element relative to the narrow spaced antenna elements. Any error in measuring the phase difference of detected signals from the narrow spaced antenna elements is compounded when that error is applied to the virtual phase difference.